Study Guide Chapter 5

Skeletal system: comprises bones, cartilage, ligaments joints and bone marrow

Bone marrow: contains hematopoietic stem cells for blood cell production

Cartilage: overview: semi - rigid connective tissue, weaker but more flexible thatn bone. Avascular (nutrients diffuse through matrix). Found between bones at joints. Types of cartilage include hyaline, fibrous, and elastic. Functions of cartilage are supporting tissues, providing gliding surface for articulations (joints), providing a model for formation of most bones in the body

Interstitial Growth of Cartilage: grows from within itself, lenghtwise at epiphyseal plate(chondrocyte mitosis, chondroblast differentiation, matrix production, cell separation)

Appositional Growth of Cartilage: Cartilage growth occurs alons the outside edge or the periphery, growth in diameter and thickness osteoblasts in periosteum add matrix osteoblasts in medullary cavity remove bone. (mesenchymay cell divison, chondroblasts differentiation, matrix secretion)

Flat bones: (thin and flat surfaces)

Long bones: (most common greater in width and length)

Short bones: (approximately equal in width and length)

Irregular bones bones with an irregular shape

Osteoprogenitor cells: stem cells in periosteum and endosteum

Osteoblasts: secrete osteoid (bone matrix)

osteocytes: maintain bone matrix (in lacunae)

osteoclasts: dissolve bone matrix (osteolysis)

Composition of bone matrix: collagen fibers: primary proteins. Ground susbtance: hydroxyapite (calcium phosphate crystals)

Gross anatomy of long bones - Diaphysis: shaft, epiphysis: expand ends (proximal and distal), metaphysis: region between diaphysis and epiphysis, articular cartilage: hyaline cartilage on epiphyses for joint articulation (reduces friction absorbs shock), medullary cavity: hallow space in diaphysis containing bone marrow, endosteum: membrane lining internal bone surface, periosteum: outermost covering (dense irregular connective tissue, perforating fibers anchors to bone )

Types of bones:

Compact bones: dense, perimeter of long bones, composed of osteons

Osteon: functional unit

Central Canal: contains blood vessels and nerves

concentric Lamellae: rings of matrix

Lacunae: spaces for osteocytes

Canaliculi: projections for osteocytes communication

Perforating canals: horizontal channels for blood vessels and nerved

Circumferential lamellae: outer layers of bone

Spongy bone: porous found in epiphyses (bottom) and center of bones, lattice like trabeculae. Trabeculae: parallel lamellae, contains lacunae and osteocytes

Intramembranous ossification: form mesenchyme forms flat bones, some facial bones, mandible and clavicle. Ossification centers form within thickened regions of mesenchyme (mesenchymal cells differentiate into osteoblasts). Osteoid undergoes calcification, trapping osteoblasts. Woven bone fomrs, periosteum develops, blood vessels penetrate. Woven bone replaced by lamellar bone then compact bone.

Endochondral ossification:from hyaline cartilage model forms most bones (limbs pelvis vertebrae). 1.fetal hyaline cartilage model develops. 2. cartilage calcifies and a periosteal bone collar forms around diaphysis. 3. primary ossification centers form in the diaphysis. 4. Secondary ossification centers forms in the epiphyses. 5. Bone replaces cartilage except the articular cartilage and epiphyseal plates. 6. Epiphyseal plates ossify and forms epiphyseal lines

Vitamin A: activates osteoblasts Vitamin C: Collagen production Vitamin D: Calcium and phosphate absorption

Healing a fracture: 1 Fracture hematoma form (blood from broken vessels). 2.Fibrocartilaginous callus forms (cartilage). 3.Hard Callus forms (ossification). 4. compact bone replaces callus